Peroxygen bleach-containing compositions have been extensively described in laundry applications as laundry detergents, laundry additives or even laundry pretreaters.
Indeed, it is known to use such peroxygen bleach-containing compositions in laundry pretreatment applications to boost the removal of encrustated stains/soils which are otherwise particularly difficult to remove, such as grease, coffee, tea, grass, mud/clay-containing soils and the like. However, we have found that a drawback associated with such peroxygen bleach-containing compositions is that said compositions may damage fabrics resulting in tensile strength loss and/or color damage when used in pretreatment application, i.e. when applied directly (neat) onto the fabrics, and left to act onto said fabrics for prolonged periods of time before washing said fabrics.
It is thus an object of the present invention to provide improved fabric safety and/or color safety to fabrics when pretreating said fabrics with peroxygen bleach-containing compositions, especially in those applications where said compositions are left neat into contact with said fabrics for prolonged periods of time before washing said fabrics.
Indeed, when pretreating fabrics with a composition comprising a peroxygen bleach like hydrogen peroxide, it has been found that the presence of metal ions such as copper and/or iron and/or manganese and/or chromium on the surface of said fabrics and/or the exposure to UV radiation from sunlight of said fabrics after having been contacted with said peroxygen bleach-containing composition, produces fabric damage resulting in loss of tensile strength of the fabric fibres and/or in color damage of said fabrics. Indeed, it is speculated that the presence of metal ions such as copper and/or iron and/or manganese and/or chromium on the surface of the fabrics, especially on cellulosic fibres, and/or the exposure of said fabrics to UV radiation from sunlight catalyse the radical decomposition of peroxygen bleaches like hydrogen peroxide. Thus, it is believed that a radical reaction occurs on the surface of the fabric with generation of free radicals, which results in tensile strength loss. Furthermore, it is speculated that this generation of free radicals may further provide an aggressive decomposition of certain dyes present in the fabrics resulting thereby in chemical damage of dye molecules which is visible as discoloration and/or hue change. Dyes commonly present in colored fabrics include metal containing dyes like copper-formazan dyes or metal azo dyes.
Therefore we have found essential that this surface reaction resulting in generation of free radicals is controlled in the pretreatment environment, thereby providing improved safety to fabrics and colors.
It has now been found that this can be achieved by formulating a peroxygen bleach-containing composition which comprises a radical scavenger, or mixtures thereof. More particularly, it has been found that the use of radical scavengers such as substituted mono and dihydroxy benzenes and derivatives thereof, alkyl- and aryl carboxylates or mixtures thereof, in a peroxygen bleach-containing composition, considerably reduces the color damage and/or fabric damage on a fabric pretreated with such a composition. Furthermore, it has been unexpectedly found that the addition, in a peroxygen bleach-containing composition, of a specific mixture of radical scavengers, i.e. the radical scavenging system as defined hereinafter, results in a synergistic effect on fabric safety and color safety when pretreating a soiled fabric with said composition.
An advantage of the present invention is that excellent laundry performance on a broad range of stains and soils such as bleachable stains and/or greasy stains is also provided.
Another advantage of the present invention is that the compositions suitable to be used according to the present invention provide also excellent performance when used in other applications, apart from laundry pretreater application, such as in other laundry applications, as a laundry detergent or laundry additive, or even in hard surface cleaning applications.
EP-B-209 228 discloses compositions comprising a peroxide source like hydrogen peroxide, metal chelating agents such as amino polyphosphonate chelants and free radical scavengers at a level of from 0.005% to 0.04% by weight of the total composition. Said radical scavengers include butyl hydroxy toluene (BHT) and mono-tert-butyl hydroquinone. The compositions exemplified comprise either BHT alone or MTBHQ. Also, nowhere it is mentioned that peroxygen bleach-containing compositions comprising a radical scavenger or mixtures thereof, allow to reduce the loss of tensile strength in fabrics and/or color damage of said fabrics, when said fabrics are pretreated with said compositions.
Co-pending European application 94870047.1 relates to highly acidic aqueous compositions containing persulfate and from 0.01% to 10% by weight of a radical scavenger, or mixtures thereof. Said radical scavengers include butyl hydroxy toluene (BHT), mono-tert-butyl hydroquinone, benzoic acid, toluic acid, t-butyl catechol, benzylamine and the like. The compositions exemplified in said patent application comprise only BHT alone. Also, nowhere it is mentioned that peroxygen bleach-containing compositions comprising a radical scavenger or mixtures thereof, allow to reduce the loss of tensile strength in fabrics and/or color damage of said fabrics, when said fabrics are pretreated with said compositions.
Co-pending European patent application 94870098.4 relates to bleaching compositions comprising a peroxygen bleach and a water-soluble cationic surfactant in combination with a hydrophilic nonionic surfactant. Said compositions may further comprise from 0.01% to 2% by weight of a radical scavenger or mixtures thereof, for stability purpose. Said radical scavengers include butyl hydroxy toluene (BHT), mono-tert-butyl hydroquinone benzoic acid, toluic acid, t-butyl catechol benzylamine and the like. None of the compositions exemplified comprises a radical scavenger nor mixtures thereof. Also, nowhere it is mentioned that peroxygen bleach-containing compositions comprising a radical scavenger or mixtures thereof, allow to reduce the loss of tensile strength in fabrics and/or color damage of said fabrics, when said fabrics are pretreated with said compositions.
Co-pending European patent application 95870018.9 discloses hydrogen peroxide-containing compositions comprising a compound chelating copper and/or iron and/or manganese, said compositions being particularly suitable to pretreat fabrics without damaging fabrics. Said compositions may further comprise from 0.001% to 0.09% by weight of a radical scavenger, or mixtures thereof. Said radical scavengers include butyl hydroxy toluene, hydroquinone, di-tert-butyl hydroquinone and the like. The compositions exemplified comprise only one radical scavenger, i.e. BHT at a level of 0.03% by weight of the total composition. Also, nowhere it is mentioned that peroxygen bleach-containing compositions comprising a radical scavenger or mixtures thereof, allow to reduce the loss of tensile strength in fabrics and/or color damage of said fabrics, when said fabrics are pretreated with said compositions.